• Peilin Ye's avatar
    audit, io_uring, io-wq: Fix memory leak in io_sq_thread() and io_wqe_worker() · f482aa98
    Peilin Ye authored
    Currently @audit_context is allocated twice for io_uring workers:
    
      1. copy_process() calls audit_alloc();
      2. io_sq_thread() or io_wqe_worker() calls audit_alloc_kernel() (which
         is effectively audit_alloc()) and overwrites @audit_context,
         causing:
    
      BUG: memory leak
      unreferenced object 0xffff888144547400 (size 1024):
    <...>
        hex dump (first 32 bytes):
          00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
          00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
        backtrace:
          [<ffffffff8135cfc3>] audit_alloc+0x133/0x210
          [<ffffffff81239e63>] copy_process+0xcd3/0x2340
          [<ffffffff8123b5f3>] create_io_thread+0x63/0x90
          [<ffffffff81686604>] create_io_worker+0xb4/0x230
          [<ffffffff81686f68>] io_wqe_enqueue+0x248/0x3b0
          [<ffffffff8167663a>] io_queue_iowq+0xba/0x200
          [<ffffffff816768b3>] io_queue_async+0x113/0x180
          [<ffffffff816840df>] io_req_task_submit+0x18f/0x1a0
          [<ffffffff816841cd>] io_apoll_task_func+0xdd/0x120
          [<ffffffff8167d49f>] tctx_task_work+0x11f/0x570
          [<ffffffff81272c4e>] task_work_run+0x7e/0xc0
          [<ffffffff8125a688>] get_signal+0xc18/0xf10
          [<ffffffff8111645b>] arch_do_signal_or_restart+0x2b/0x730
          [<ffffffff812ea44e>] exit_to_user_mode_prepare+0x5e/0x180
          [<ffffffff844ae1b2>] syscall_exit_to_user_mode+0x12/0x20
          [<ffffffff844a7e80>] do_syscall_64+0x40/0x80
    
    Then,
    
      3. io_sq_thread() or io_wqe_worker() frees @audit_context using
         audit_free();
      4. do_exit() eventually calls audit_free() again, which is okay
         because audit_free() does a NULL check.
    
    As suggested by Paul Moore, fix it by deleting audit_alloc_kernel() and
    redundant audit_free() calls.
    
    Fixes: 5bd2182d ("audit,io_uring,io-wq: add some basic audit support to io_uring")
    Suggested-by: default avatarPaul Moore <paul@paul-moore.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarPeilin Ye <peilin.ye@bytedance.com>
    Acked-by: default avatarPaul Moore <paul@paul-moore.com>
    Link: https://lore.kernel.org/r/20220803222343.31673-1-yepeilin.cs@gmail.comSigned-off-by: default avatarJens Axboe <axboe@kernel.dk>
    f482aa98
auditsc.c 80.8 KB